After a troubled year in 2014, the global tablet market is not returning to the levels of growth seen in the last four years as demand for tablets will continue to be slow in 2015.

Gartner estimates that worldwide tablet sales will reach 233-million units in 2015, an 8% increase from 2014.

“The collapse of the tablet market in 2014 was alarming,” says Ranjit Atwal, research director at Gartner. “In the last two years global sales of tablets were growing in double-digits. The steep drop can be explained by several factors. One is that the lifetime of tablets is being extended – they are shared out amongst family members and software upgrades, especially for iOS devices, keep the tablets current.

ÔÇťAnother factor includes the lack of innovation in hardware which prevents consumers from upgrading.

Worldwide combined shipments of devices (PCs, tablets, ultramobiles and mobile phones) for 2015 are estimated to reach 2,5-billion units, an increase of 3,9% over 2014.

The mobile phone segment is on pace to grow 3,7% in 2015 and reach 2-billion units in 2016.

“The smartphone market is becoming polarized between the high- and low-end market price points,” says Annette Zimmermann, research director at Gartner.

“On one hand, the premium phone with an average selling price at $447 in 2014 saw growth dominated by iOS, and on the other end of the spectrum you have Android and other open OS phones’ growth area in the basic phone segment, where the average phone costs $100. For the midrange smartphones, the market opportunity is becoming increasingly limited.”

In the operating system (OS) market, Android surpassed a billion shipments of devices in 2014, and will continue to grow at a double-digit pace in 2015, with a 26% increase year-over-year.

“From 2015, we expect Windows to grow faster than iOS, as the PC market stabilizes and the challenge for the next iPhone to find significant growth becomes greater, narrowing the gap between the two operating systems,” says Atwal.